Yarn guide element



Oct. 17, 1961 A. c. sPlvEY YARN GUIDE ELEMENT Filed June 4. 1959 INE/ENTOR A/vd. Sylva] ATTORNEY 3,004,733 YARN GUIDE ELEMENT Alva C. Spivey, 2539 Jefferson St., Paducah, Ky. Filed June 4, 1959, Ser. No. 818,149 3 Claims. (Cl. 242-157) This is a continuation-impart of'rny application entitled Yarn Guide Element which was filed February 19,

1957, Serial No. 641,068, now abandoned.

l This inventionrelates to a yarn guiding element for use on knitting machines and other yarn handling and utilizing machines. f

In recent years, since synthetic yarns yhave come into extensive use, the problem of devising yarn guiding elements has become more acute, since the synthetic yarns, such as nylon, cause excessive wear of surfaces over which they travel in the course of being introduced into andutilized in textile machines. Metal guiding surfaces,

'even though made of special steels treated to improve theirhardness and finish to a smooth surface, are soon worn by the nylon to the extent that they must be replaced or repaired. These problems have been overcome in certain instances, especially in thread guides employing eyelets, tubes, corner button guides, rollers, pigtails, condensers, and the like, by employing a ceramic insert. The extreme hardness and smoothness which can be attained with ceramic has proven to be more satisfactory than metal guiding surfaces. As ya result, guiding elements such as those named above have been made to include ceramic bearing surfaces in recent years. However, certain parts Aof textile machines are subjected to vibration, or strains resulting from'fastening the parts into the machine, and the characteristic properties of ceramic, which give it desirable yarn guiding characteristics, have made it impossible to use ceramic in s-uch elements, Vas they are easily fractured by such strains. One of the unsuccessful applications of ceramics due to lthese -factors has been in the manufacture of the throat plate commonly employed on circularknitting machines. This plate has a substantial area, insofar as ceramic elements are concerned, and is fastened rigidly into the 'knitting machine. The yarn traveling fromrthe supply to the needles o f the machine passes across the throat plate and downwardly from the forward edge tothe knitting machine. In the course of operation of the machine, thethread moves backwardly and forwardly across the plate and, especially in the case of nylon, the edge of the plate, particularly in the lateral corners, is wornunevenly and results in undesired tension on the thread as well as c ausingbreaking of the thread in some instances. Such throat plates are commonly made of special hard steels, which are carefully finished. -The cost Vof the plate is substantial, and the expense of refinishing or replacing it lfrom time to time is one of the major items of upkeep on such machines. The purposes and objectives of the present invention can be illustrated by showing its application to throat plates.

According to the present invention, a ceramic thread guiding surface is supported in such a manner that it is positively retained against displacement in the machine but without subjecting it to strains which will cause it to break in the course of being so maintained, and which will protect it against shocks and vibrations which occur in the course of the machines operation.

According to the present invention a ceramic insert is so formed and shaped that it may be received by a shock and strain absorbing base member which has a cooperating configuration which maintains the insert in place. The base member is provided with necessary apertures common to throat plates which permit it to be fastened by screws into the machine. No fastening elements or adhesives are required on the ceramic insert, and any distortion which is occasioned by fastening the assembly of the base and insert into the machines is taken up locally by the base itself, and such strains 'are not transmitted to the insert. This illustrative' application of the invention is shown in the accompanying drawings, and described in detail hereinafter. Y

In the drawings:

FIGURE l is a top plan view of a base member;

FIGURE 2 is a front elevational view of the same base member;

FIGURE 3 is a top plan view of a ceramic insert accordin-gl to the invention;

FIGURE 4 is a front elevational view of the same insert;

FIGURE 5 is a top plan view of the base and insert assembled;

FIGURE 6 is a front elevational View of the same assembly;

FIGURE 7 is a bottom plan view of the same assembly; f

FIGURE 8 is a top plan view of another form of throat plate according to the invention;

FIGURE 9 is a side elevational View of the element shown in FIGURE 8;

FIGURE 10 is a bottom plan view of the same element; and

FIGURE l1 is a sectional view of the same element on line 11-11 of FIGURE 8.

Referring to FIGURES 1 and 2, it may be seen that the base is a channel-like member having a bottom 10 and upstanding side walls 12, '14 at the lateral edges of the bottom. Theseside walls are provided with apertures 1x6, 18 through which screws may be inserted to x the base member in place on the machine. The forward edges of the side walls have formed integrally therewith blocks 20, 22, whose mutually facing vertical sides are inclined outwardly to provide notches 24, 26. This base is preferably made of nylon, or other plastic having substantially the same properties of strength, toughness, ilexibility and shock cushioning.

Referring to FIGURES 3 and 4, it may be seen that the ceramic insert is also a channel-like member having a Vbase Z8 and at the lateral 'edges thereof upstanding portions 39, 32 which are trapezoidal in cross section. The laterally extending wings 34, 36 are formed integrally with the upper edge of these upstanding portions as may be seen best in FIGURE 4. It will be noted that the forward edge 3S of the insert is curved concavely and it is over this edge that the yarn passes While traveling from the supply to the needles of the machine. The manner in which the ceramic insert is received by the base is illustrated in FIGURES 5 and 6. It will be seen that the trapezoidal sections 30, 32 are received in the notches 24, 26. The upper portion of the blocks 20, 22 of the base element terminate a distance vertically beneath the top edges of the side walls 12, 14 of the base that corresponds to the vertical thickness of the wings 34, 36 of the insert. Accordingly, when the insert is assembled with in some instances.

the base, the upper horizontal surfaces of the wings 34, 36 are diush with the upper horizontal surfaces of the side walls 12, 14 of the base element, as shown best in FIGURE 6. Inasmuch as the elements 30, 32 of the insert are positioned in the notches 24, 26, the insert cannot be displaced either lforwardly or backwardly. As the wings 34, 36 overlie the top edge of the blocks 20, 22, the insert is secured against downward displacement. When Iassembled in the machine, the insert is prevented from moving upwardly, by virtue of the assembly being held against an overlying surface by, means of the screws which are inserted through the apertures 16, 18. Referring to FIGURE 7, 40 indicates metal Washers which 'rest on shoulders provided within the Vapertures 16, 18

land against which the heads of the fastening screws bear. These was-hers prevent the heads of the fastening screws from cutting into the plastic material from which the base member is formed. v Accordingly, the ceramic insert cannot be displaced in any direction, and at'the same time, is not subjected to strains which cause it to break. The insert itself is not fastened by screws to either the machine `or the base element, and is thus isolated from the strains of s-uch fastening-as well as Ifrom vibrations or shocks caused by operation of the machine.

It is desirable in most instances toemploy a fil-ler, preferably an adhesive one, between the contacting surfaces of the insert and the base member. This serves primarily to provide a right lit between the base member and the insert which is difficult and impractical to achieve by forming each of these elements with the precision which would be required so that there would be no relative movement between them in the absence of the filler. If the iller is in the nature of adhesive material also, this has the added advantage of preventing accidental displacement of the insert yfrom the base piece prior to assembly of the throat plate on the machine.

Another form of throat plate according to the invenl tion is illustrated in FIGURES 8-11. The ceramic insert used therein is similar to that describedfabove, but the base is modiied to the extent that the lower rearward portion thereof is replaced by a metal element 42, Which is proportioned so that it makes up the portion upon which the yarn lingers strike, but accommodates a portion of the nylon base between its forward edge and lche rearward edge of the ceramic insert. This larrangement does not detract from the shook absorbing properties of the base which are necessary to prevent breakage of the ceramic insert, but does serve to minimize the tendency of the yarn lingers to bounce upon dropping onto the plate. The metal element 42 may be secured towthe plastic portion of the base by adhesive, although the hold-down screw passing through the notches 16, 18 lact to hold these elements together also.

A satisfactory ceramic Ifor forming the insert according to this invention may consist of the type of ceramic material which is described in U.S. Patent No. 2,3 69,266 to Thurnauer, issued February l13, 1945. It is not necessary, however, that the ceramic have the electrical properties therein described, although these may be desirable invention may be identified by the following characteristics:

Hardness, Mohs scale 8-9 Resistance to impact, Charpy, Y

pounds per square inch 2.4-6.3 Flexional strength, pounds per square inch 20,000\-40,000 Compressive strength, pounds per square inch 80,000l`00,000 Density, pounds per cubic inch' .095-.123 Water absorption Nil Resistance to Iheat 1,000 C.-l,l00 C. Thermal conductivity .012-.02

AlSiMags, products of the American Lava Corporation, are satisfactory ceramic materials. U,S. Patent No. 2,214,703 to Thurnauer describes ceramic materials satisfactory -for the present invention.

It will be appreciated that the above characteristics are exemplary of the ceramic materials which may be ernployed, -and that the inventionmaybe embodied in various -forrns other than that illustrated and described specifically above, and that other specific interlocking t designs nmay be 'employed to retain the hard, brittle Ceramics having properties satiskfactory for the` manfuacture or inserts according to this cer-amic insert in position on the base member in such `manner that the strains which accompany lfastening the assembly to the machine, and employing it, may be taken `up locally bythe base element consisting of a plastic material of which-nylon, described above, is exemplary. Having thus described the invention, What is claimed .as new and desired to be secured by Letters Patent is:

1. A yarn guide comprising a solid base member formed from shock and strain resistant plastic and having an end face, a recess formed in said end -fac`e extending in the direction of the recess axis through one dimension of said face and in a transverse direction less than the corresponding dimension of said face so as to terminate short ofthe edgesof said Iface, iand opposed notches cut into said -face on either side of said recess, said notches communicating with said recess; and an insert of wear- `resistant ceramic material disposed within said recess and restrained thereby against movement in said transverse direction, said insert having extensions projecting laterally therefrom, said extensions being received within the notches in the face of said base member and serving to restrain the insert against axial movement relative to the recess axis in at least one direction.

2. A yarn guide as -in claim 1y wherein the transverse dimension of the vrecess is greater at a locus spaced inwardly of said face than at said face and said insert is correspondingly ,shaped to fit therewithin.` v

3. A'yarn guide kas in claim 1 vwherein said base member includes a top -face extending at an angle toy said end face and said notches extend through both saidrend face and said top -face whereby said insert is restrained against downward movement relative to said topfface.

References Cited in the file of this patent UNITED STATES' PATENTS McKinley et al July 28, 1959 

